1. Field of the Invention
The present invention relates to a wireless laryngoscope and camera system, and more particularly to a wireless laryngoscope with onboard recording that is particularly well suited for laryngoscopy training.
2. Background Information
Dr. Richard M. Cooper of the Department of Anesthesia and Pain Management, Toronto General Hospital, University of Toronto has eloquently introduced the need and purpose for laryngoscope noting that “man's assumption of an upright posture, coupled with our tendency to live in social groups has resulted in some bad habits—simultaneous eating and talking. This has necessitated exclusion of the larynx from the line of sight connecting the mouth to the esophagus. While this does make eating safer and more interesting, it has complicated the task for airway managers.”
Brief History of Laryngology
The early need for laryngeal visualization was noted by medical student Benjamin Guy Babington who created a “glottiscope” in 1829. A two pronged tool, one prong (or shank) depressed the tongue while the other was positioned along the palate, reflecting sunlight for illumination of the glottis. This device was later termed a laryngoscope by his contemporaries. In 1844, John Avery, a surgeon at London's Charing Cross Hospital developed a head-mounted mirror that reflected candlelight onto a mirror housed within a speculum. Manual Garcia (1805-1906), a professor of singing at the Royal Academy of Music in London is generally credited with the discovery of laryngoscopy. In 1854, while strolling in Paris, he saw the sun's image reflected in a store windowpane. He purchased a dental mirror for six francs and used this, in combination with a hand-held mirror reflecting sunlight, to visualize his own larynx and trachea during inspiration and vocalization. His discovery, which he termed “autolaryngoscopy” was presented to the Royal Society in May 1855 and at the age of 100, in 1905 he was honored by the most prominent laryngologists of his time as the Father of laryngology.
Ludwig Türck, a Viennese neurologist used a technique similar to Garcia's, though apparently unaware of the singing teacher's activities. He used self-made mirrors and performed laryngoscopy on his gagging patients until the autumn sun's diminished intensity forced him to abandon his efforts. Johann Czermak, a physician and physiologist from Budapest, using a table lamp and mirrors borrowed from Türck, performed laryngoscopy. Czermak published and demonstrated his findings widely. He initially acknowledged Türck's contribution, but subsequently withdrew this. What followed was a protracted public debate, referred to as the “Türckish war” about who actually first used laryngoscopy for diagnostic purposes.
A laryngology clinic was established in Vienna in 1870 and minor surgical procedures were performed under visual control. In the days prior to local anesthetics, patients had to be trained to suppress their gag reflexes. Morell Mackenzie learned laryngoscopy from Czermak and went on to found London's first throat hospital.
William Macewen, a British surgeon, was the first to intubate the larynx for surgical purposes. He practiced blind, digital intubation on cadavers and eventually employed this technique to perform a composite resection in 1878. Joseph O'Dwyer developed instruments to enable tracheal intubation which saved the lives of hundreds of children suffocating from diphtheria. Hans Kuhn modified O'Dwyer's instruments and created a long, flexible metal endotracheal tube and introducer but the technique still depended upon blind insertion, largely because light sources were inadequate to permit progress in direct laryngoscopy.
In 1895, Alfred Kirstein learned of an inadvertent tracheal insertion of an esophagoscope, and proceeded to develop a rigid laryngoscope with transmitted light. This consisted of a lamp within the handle, focused on a lens and redirected through the laryngoscope by a prism. Chevalier Jackson subsequently modified Kirstein's laryngoscope by providing distal illumination with a tungsten bulb. In 1913, Henry Janeway devised an open-sided laryngoscope with battery operated distal illumination, specifically for endotracheal intubation.
In 1941, Robert Miller introduced a new, longer, lower profile laryngoscope blade (a straighter blade), designed to pick up the epiglottis. This blade required limited mouth opening but also left little space to manipulate the endotracheal tube (ETT). Two years later, Robert Macintosh described a curved blade, designed to elevate the epiglottis by exerting its force on the base of the tongue. He believed that reducing contact with the epiglottis would be less stimulating and provide more room for manipulation of the ETT. These two blade designs, known as the “Miller blade” and the “Mac blade” or “Macintosh Blade” were quickly and widely adopted.
Modern Laryngoscopy
The “Miller blade” and the “Mac blade” or “Macintosh Blade” both continue to dominate the field of laryngoscopy and these blade forms represent more than 95% of the laryngoscopic blades used in practice. The proper function of both a Macintosh and Miller blade is dependent on using an appropriate length of blade. The Macintosh blade must be long enough to put tension on the glossoepiglottic ligament, and the Miller blade must be long enough to trap the epiglottis against the tongue. Both blade types are made in various designated sizes (but the overall distinctive shape is as described above). Thus, in some patients, it may be appropriate to change the length of the conventional Mac or Miller blade in order to obtain proper blade function. The changing of the length can be through replaceable blades that is common in laryngoscopes or through selecting a separate laryngoscope altogether.
In some patients, a Macintosh blade may provide a superior view or intubating conditions than a Miller blade, and vice versa. A Macintosh blade is generally regarded as a better blade whenever there is little upper airway room to pass the ET (e.g., small narrow mouth, palate, oropharynx), and a Miller blade is generally regarded as a better blade in patients who have a small mandibular space (anterior larynx), large incisors, or a long, floppy epiglottis. Although the skill that the practitioner has with each style may also be determinative of which design is best suited for particular applications.
A study that examined airway problems in over 18,500 adult non-obstetrical patients, direct larynoscopy was the first choice 98% of the time. Among these patients, the failure rate was 0.3% and “awkward” or “difficult” in 2.5% and 1.8% respectively. The study recognized that difficulties involving laryngoscopy and intubation are poorly described and proposed an intubation “difficulty score”. No difficulties were encountered in 55% of adult patients; minor intubations difficulties were encountered in 37%; two or three laryngoscopies were required in 9% of cases and more than three attempts were required 3% of the time. However, even “non-difficult” endotracheal intubation may be associated with airway injury. One analysis involving 266 incidents of airway injury found that 80% of laryngeal injuries occurred when laryngoscopy and intubation was thought to have been easy.
The inability to properly visualize the larynx generally results in multiple or prolonged laryngoscopic attempts with increasing force, and is associated with esophageal, pharyngeal and dental injury, arterial desaturation, hemodynamic instability and unplanned intensive care unit admissions.
More recently, compact, robust, high-resolution video-chips have become available which can be embedded within laryngoscopes. These devices provide an alternative laryngeal view. These devices permit simultaneous viewing by mentor and supervisor and have been thought to accelerate the instruction of laryngoscopy. These images can be captured and replayed for analysis to further expedite and improve training. The video or static images may be useful for research, teaching or clinical documentation. Also, these devices can enable visualization in settings that would otherwise be challenging or not possible. Additionally, it has been asserted that since tissues do not have to be compressed and distracted to achieve a line-of-sight, there may be less stress and trauma to the patient during laryngoscopy; and further that, positioning should not impact upon the laryngeal view.
Several different laryngoscopes with associated camera systems have been commercialized to some degree or another, with each system allowing for indirect viewing of obstructed airways. All of these systems rely on standard wired camera technologies to provide the intubator and other medical personnel with an indirect visualization of the field on view. The digital images from these commercial camera systems are transmitted via cable to an external monitor.
The inherent weaknesses of the systems using external viewing displays are that the cables connecting the camera, to the display, limits the movement of the intubator, which may complicate an already difficult procedure. An attached cable limits the working space for medical personnel and can also cause another potential hazard. Also, having exposed cabling leaves the system susceptible to fluids damaging the sensitive electronic systems no matter how well sealed. Furthermore, cables are easily damaged from over extension, frequent use, and any number of other factors adding a substantial point of failure to the entire system.
Wireless transmitters for such systems have been proposed that could, in theory, alleviate the problems encountered with cabled camera systems. See for example U.S. Patent Application Publication 2003/0195390 and U.S. Pat. No. 6,840,903, which are incorporated herein by reference. In both these systems the cable is replaced with an external antennae attached to a transmitter. The external antennae in each of these proposed wireless systems add a separate obstruction on the laryngoscope for the user. Further, as noted above, a significant advantage for the use of camera systems in laryngoscopes is for teaching and training purposes. Both of these prior art camera systems are directed to “specialized” blade shapes (non Miller or Mac styles), and promote the advantages of such unique blades.
The inventors of the present invention believe that training on “specialized” blades is not useful and possibly counter productive. Having trainees gain proficiency on a blade design they are not likely to see in the actual use is less desirable (and possibly counter productive) than having them gain proficiency on conventional blade designs. Within the meaning of this application the Mac blades (AKA Macintosh blades) and the Miller blades, as known in the art, are “conventional” blade designs for laryngoscopes.
Other prior art laryngoscopy related developments can be found in U.S. Pat. No. 6,652,453 disclosing a portable video laryngoscope; U.S. Pat. No. 6,840,903 by Nuvista Technology Company disclosing a laryngoscope with image sensor; U.S. Pat. No. 6,890,298 by Karl Storz GmbH & Co disclosing a video laryngoscope with a detachable light and image guide; and U.S. Patent Publication No. 2003/0195390 disclosing a digital laryngoscope with image sensor. These patents and published patent application are incorporated herein by reference.
Some of the inventors of the present application were also inventors of a prior laryngoscopy training aid disclosed in U.S. Patent 2007-0179342 which is incorporated herein by reference. As discussed in detail in the following application, the present invention includes substantially all of the advantages of the laryngoscopy training aid disclosed in U.S. Patent 2007-0179342 including the provision of (a) a wireless laryngoscope for remote viewing and capable of serving as an intubation instrument, for standard intubations and complicated intubations where the field of view is obstructed from the intubator and/or other medical staff; (b) a laryngoscope, which is similar in design and functionality to existing blade and handle shapes so that the intubator is familiar with its application, and such that the laryngoscope is particularly well suited for training applications; and (c) an electronic laryngoscope with a self-contained wireless digital camera embedded within the laryngoscope, which provides real-time indirect viewing of the field of view that is also self-contained, light weight, and portable, and wherein this image may selectively be transmitted wirelessly to a remote receiver and can be viewed on any video type display.
The prior laryngoscopy training aid disclosed and described in U.S. Patent 2007-0179342 however fails to provide on-board recording capable of capturing audio, video, and/or event data, or on-Board event flagging. It is an object of the present invention to maintain substantially all of the advantages of the prior laryngoscopy training aid disclosed in U.S. Patent 2007-0179342 and address the deficiencies of this prior art system.